Engine starter



Dec. 7, 1937. J. AYRES 2,101,606

ENGINE STARTER Filed Jan. 4, 1957 Fig. 1.

INVENTOK m 5 ATTORNEY;

Patented Dec. 7, 1937 UNITED STATES PATENT OFFICE ENGINE STARTER John Ayres, Carahalton arm Limited, Hackbrldge,

England, assignor to Surrey, England 12 Claims.

In electrical engine starters, where a small electrical motor, having its supply from a battery or accumulator, is used to turn the engine over at a speed sufllcient to ensure firing, two types of drive are common, viz., the inertia type, in which the starter pinion by reason of its inertia is caused to thread itself along a quick pitch screwed shaft into engagement with the engine flywheel, and the axial type, where the starter pinion is directly coupled to the motor shaft which is caused to move longitudinally to engage the pinion by the magnetic influence of the motor field winding.

A difllculty associated with such starters is that the sudden application of load on to the starter motor, caused by the engagement of the pinion into the engine flywheel, often results in, mechanical breakdown occasioned by a jammed drive, a bent shaft, a stripped flywheel gear or a broken spring where a spring is incorporated. Moreover, since the drive locks solid when subject to a reversal of rotation, a severe back-fire" (such as sometimes occurs, for example, in a compression ignition type engine) may also cause breakdown of the engine starter.

Many attempts have been made to overcome the above difiiculties, notably by the inclusion of plate clutches arranged to .slip when subjected to excessive torque, and spring drives which take up the initial shock of engagement and uncoil when the engine back-fires to release the drive.

An object of this invention is to achieve the desired result in a simplified, inexpensive and practical manner.

In accordance with the invention, fluid coupling means (hereinafter termed hydraulic coupling) is interposed between the starter motor and the starter pinion to protect the mechanical parts of the starter against excessive shocks and 40 consequent breakdown under all eventualities likely to occur during the operation of the starter. I

Preferably the driven member of the hydraulic coupling is splined or slidably mounted on the starter pinion shaft and spring-urged into frictional engagement with the co-acting driving member which is positively rotatable with the motor armature shaft.

With such an arrangement the application of the load (on engagement of the starter pinion with the engine fly-wheel consequent on the setting into operation of the starter) may stop rotation of the pinion and driven coupling member, causing such movement of the fluid in the coupling (under continued rotation of motor and driving coupling'member) as. to decelerate the motor and increase its torque until this is willcient to begin turning the engine, whereafter the speed of the starter increases until the engine runs under its own power. Should a backfire occur, the pinion and driven coupling member will be rotated in the reverse direction and the starter motor will be slowed up without shock as a result of the reaction that occurs between the coupling members.

By way of example a form of starter embodying the foregoing and other features of the invention is illustrated on the accompanying drawing.

Fig. 1 shows the starter partly in longitudinal section.

Fig. 2 is a fragmentary end view of the driven member of the hydraulic coupling.

The starter motor may be of the series torque characteristic type or a high speed shunt wound machine may be employed having a slightly compounded characterlstic, the speed of the motor being arranged to suit the characteristics of the hydraulic coupling.

Reference i denotes the starter motor frame or housing, 2 the field system, 3 the armature, and l the armature shaft which is supported by anti-friction bearings 5, 5.

The armature shaft 4 is finished in the form of a taper upon which is fitted a flywheel 6 which also forms the outer casing of a hydraulic coupling or clutch. The flywheel is secured to the armature shaft by means of a stud 1 having its outer end recessed to form a thrust cup 8.

The combined outer casing and flywheel 6 is also fixed at its extermity to a driving member 9, which has around its periphery concave fluid galleries l0 suitably partitioned. The driving member loosely surrounds a starter pinion shaft H mounted in a. bearing Ila in axial alignment with the motor armature shaft 4. The driven member I 2 of the hydraulic coupling is splined or keyed at Ma to the pinion shaft, being free to move longitudinally between certain limits, and has fluid galleries Ill (see also Fig. 2) to match those in the driving member 9. 25 denotes an anti-friction bearing between the driven member and the combined outer casing and flywheel 6. A locking collar I 3 on the pinion shaft suitably positions and retains the driven member I2. The end of the locking collar is shaped in the form of a button I to co-act with the aforesaid thrust cup 8 and take the thrust during operation.

The hydraulic arrangement is rendered fluid- 55 tight by the inclusion of a stufllng gland ii for the driving coupling member 9 which gland is held in position by a gland nut l6.

Interposed between the driving and driven members 9, l2 of the coupling is a friction disc ll of suitable material, while a coiled tension spring I8 is included between the locking collar l3 and the outer casing 6 of the coupling for the purposeof holding the driving and driven members of the coupling in contact with the friction disc. This spring bears against a thrust race I80. carried by the locking collar 13. I

The outer end of the pinion shaft II has fixed to it a sleeve threaded externally with a quick pitch screw, and the starter pinion 20 is screwed internally to suit. Front and back stop collars- 2i and 22 pinned to the pinion shaft and sleeve limit the axial movements of the pinion on the sleeve.

28 denotes the engine flywheel and 24 the toothed starter ring thereon to be engaged by the starter pinion 20.

When the electrical circuit to the starter motor is completed (by pressure of the conventional switch button or by any other means) the armature shaft 4 rotates, taking with it the combined outer casing and flywheel 6 and therefore the driving member 5 of the hydraulic coupling. Since the driven member i2 of the coupling is in contact with the driving member through the friction disc II, this also is rotated, together with the pinion shaft Ii. The pinion 20, by reason of its inertia, is therefore threaded along the sleeve i9 until engagement with the engine flywheel starter ring 24 is accomplished and the pinion comes up against the stop collar 22. Immediately this occurs, the application ofthe load caused by the engagement stops the pinion shaft ii and, consequently, the driven member i2 of the hydraulic coupling. With the electric motor still supplied with power, and therefore rotating, maximum slip occurs between the driving and driven members 9, H of the hydraulic coupling, and therefore maximum agitation of the-fluid in the hydraulic coupling, giving maximum turning effort. The speed of the starter motor is reduced and its torque is therefore increased, while the driven member i2 of the coupling is forced away from the driving member along the spline or key Hut and against the tension spring i8 by the pres sure of the-fluid in the galleries it. This brings the thrust button M on to its seating 8 and relieves the friction disc i'l, allowing the latter to run free. The motor continues to decelerate until the shaft torque is suiiicient to commence turning the engine, after which the speed of the starter increases until the engine fires under its own power. All this is accomplished without shock to the mechanical drive, thehydraulic coupling making all adjustments smoothly and safely.

When the engine fires, the pinion is momentarily rotated faster than the starter motor shaft and is therefore threaded out of engagement with the engine flywheel starter ring 24.

Should a back-fire occur, both torque and rotation are reversed, so that the pinion remains solid with the pinion shaft. The pinion, pinion shaft and driven member of the hydraulic cou-.

pling are therefore reversed in rotation, which has the effect of causing a greater reaction between the two-members of the coupling, thereby slowing up the starter motor. There is, however, no excessive shock to the mechanical part of the drive, the coupling again acting as the necessary cus io I. An engine starter including an electric motorand a pinion arranged to be driven from. the motor armature shaft, characterized by fluid coupling means interposed between the motor and the pinion for protecting the starter against excessive load and back-fire shocks and consequent breakdown during operation, said coupling means comprising a driving member positively rotatable-with the motor armature shaft, a co-acting driven member, and spring means urging the driven member into frictional engagement with said driving member.

2. In an engine starter including an electric motor and a pinion supporting shaft arranged to be driven from the motor armature shaft, a fluid coupling interposed between the motor and the pinion shaft, said coupling comprising a combined outer casing and flywheel secured to the motor armature shaft, a driving member with interior fluid galleries secured at its periphery to the combined outer casing and flywheel, a co-acting driven member with similar interior fluid galleries rotatable with and axially movable on the pinion shaft, and resilient means urging the driving and driven members into frictional engagement.

3. In an engine starter including an electric motor and a pinion supporting shaft arranged to be driven from the motor armature shaft, a fluid coupling interposed between the motor and the pinion shaft, said coupling comprising a combined outer casing and flywheel secured to the motor armature shaft, a driving member with interior fluid galleries secured at its periphery to the combined outer casing and flywheel, a coacting driven member with similar interior fluid galleries rotatable with andaxially movable on the pinion shaft, a collar retaining the driven member on the pinion shaft, and resilient means between the combined-outer casing and flywheel and the collar for urging the driving and drivenmembers into frictional engagement.

4..In an engine starter including an electric motor and a pinion supporting shaft arranged to be driven from the motor armature shaft, a fluid coupling interposed between the motor and the pinion shaft, said coupling comprising a combined outer casing and flywheel secured to the.

, driving and driven members into frictional engagement.

5. In an engine starter including an electric motor and a pinion supporting shaft arranged to be driven from the motor armature shaft, a fluid coupling interposed between the motor and the pinion shaft, said coupling comprising a combined outer casing and flywheel secured to the motor armature shaft, a driving member with interior fluid galleries secured at its periphery to the combined outer casing and flywheel, a coactlng driven member with similar interior fluid galleries rotatable with and axially movable on the pinion shaft, a stud securing the combined outer casing and flywheel to the motor armature shaft and presenting a thrust cup, a collar retaining the driven member on the pinion shaft and forming a button to co-act with the thrust cup, and resilient means between the combined outer casing and flywheel and the collar for urging the driving and driven members into frictional engagement.

6. In an engine starter including an electric motor and a pinion supporting shaft arranged to be driven from the motor armature shaft, a fluid coupling interposed between the motor and the pinion shaft, said coupling comprising a combined outer casing and flywheel secured to the motor armature shaft, a driving member with interior fluid galleries secured at its periphery to the combined outer casing and flywheel, a co-acting driven member with similar interior fluid galleries rotatable with and axially movable on the pinion shaft, a stud securing the combined outer casing and flywheel to the motor armature shaft and presenting a thrust cup, a collar retaining the driven member on the p nion shaft and forming a button to co-act with the thrust cup, a thrust race carried by the collar, and resilient means between the combined outer casing and flywheel and the thrust race for urging the driving and driven members into frictional engagement.

7. In an engine starter including an electric motor and a pinion supporting shaft arranged to be driven from the motor armature shaft, a fluid coupling interposed between the motor and the pinion shaft, said coupling comprising a combined outer casing and flywheel secured to the motor armature shaft, a driving member with interior fluid galleries secured at its periphery to the combined outer casing and flywheel, a co-acting driven member with similar interior fluid galleries rotatable with and axially movable on the pinion shaft, an anti-friction bearing interposed between the driven member and the combined outer casing and flywheel, and resilient means urging the driving and driven members into frictional engagement.

8. In an engine starter including an electric motor and a pinion supporting shaft arranged to be driven from the motor armature shaft, a fluid coupling interposed between the motor and the pinion shaft, said coupling comprising a combined outer casing and flywheel secured to the motor armature shaft, a driving member with interior fluid galleries secured at its periphery to the combined outer casing and flywheel, a co-acting driven member with similar interior fluid galleries rotatable with and axially movable on the pinion shaft, a stufling gland and g and nut sealing the driving member with respect to the starter pinion shaft, and resilient means urging the driving and driven members into frictional engagement.

9. In an engine starter including an electric motor and a pinion supporting shaft arranged to be driven from the motor armature shaft, 9. fluid coupling interposed between the motor and the pinion shaft, said coupling comprising a combined outer casing and flywheel secured to the motor armature shaft, a driving member with interior fluid galleries secured at its periphery to the combined outer casing and flywheel, a co-acting driven member with similar interior fluid galleries rotatable with and axially movable on the pinion shaft, a stuffing gland and gland nut sealing thedriving member with respect to the starter pinion shaft, an anti-friction bearing interposed between the driven member and the combined outer casing and flywheel, and resilient means urging the driving and driven members into frictional engagement.

10. In an engine starter including an electric motor and a pinion supporting shaft arranged to be driven from the motor armature shaft, a fluid coupling interposed between the motor and the pinion shaft, said coupling comprising a combined outer casing and flywheel secured to the motor armature shaft, a driving member with interior fluid galleries secured at its periphery to the combined outer casing and flywheel, a co-acting driven member with similar interior fluid galleries rotatable with and axially movable on the pinion shaft, a stufling gland and gland nut sealing the driving member with respect to the starter pinion shaft, a collar retain ng the driven member on the pinion shaft, and resilient means between the combined outer casing and flywheel and the collar for urging the driving and driven members into frictional engagement.

11. In an engine starter including an electric motor and a pinion supporting shaft arranged to be driven from the motor armature shaft, a fluid coupling interposed between the motor and the pinion shaft, said coupling comprising a combined outer casing and flywheel secured to the motor armature shaft, a driving member with interior fluid galleries secured at its periphery to the combined outer casing and flywheel, a co-acting driven member with similar interior fluid galleries rotatable with and axially movable on the pinion shaft, a stufllng gland and gland nut sealing the driving member with respect to the starter pinion shaft, an anti-friction bearing interposed between the driven member and the combined outer casing and flywheel, a collar retaining the driven member on the pinion shaft, a thrust race carried by the collar, and resilient means between the combined outer casing and flywheel and the thrust race for urging the driving and driven members into frictional engagement.

12. In an engine starter including an electric motor and a pinion supporting shaft arranged to be driven from the motor armature shaft, 9. fluid coupling interposed between the motor and the pinion shaft, said coupling comprising a combined outer casing and flywheel secured to the motor armature shaft, a driving member with interior fluid galleries secured at its periphery to the combined outer casing and flywheel, a coacting driven member with similar interior fluid galleries rotatable with and axially movable on the pinion shaft, resilient means urging the driving and driven members into frictional engagement, an anti-friction bearing between the driven member and the combined outer casing and flywheel, and a stufllng gland and gland nut sealing the driving member with respect to the pinion shaft.

JOHN AYE-l8. 

